On-press development type lithographic printing plate precursor, method of preparing lithographic printing plate, and lithographic printing method

Abstract

An on-press development type lithographic printing plate precursor including a support and an image-recording layer on the support, in which the image-recording layer contains a polymerizable compound, a polymerization initiator, and an infrared absorber, and a color forming substance precursor, and a color forming substance generated from the color forming substance precursor has a maximal absorption wavelength in a wavelength range of 380 nm or more and less than 580 nm, at which an absorbance difference with respect to the color forming substance precursor is 0.1 or more, and a maximal absorption wavelength in a wavelength range of 580 nm or more and 750 nm or less, at which an absorbance difference with respect to the color forming substance precursor is 0.07 or more, and a method of preparing lithographic printing plate or a lithographic printing method, using the on-press development type lithographic printing plate precursor.

What is claimed is: 
     
         1 . An on-press development type lithographic printing plate precursor, comprising:
 a support; and   an image-recording layer on the support,   wherein the image-recording layer contains a polymerizable compound, a polymerization initiator, an infrared absorber, and a color forming substance precursor, and   a color forming substance generated from the color forming substance precursor has
 a maximal absorption wavelength in a wavelength range of 380 nm or more and less than 580 nm, at which an absorbance difference with respect to the color forming substance precursor is 0.1 or more, and 
 a maximal absorption wavelength in a wavelength range of 580 nm or more and 750 nm or less, at which an absorbance difference with respect to the color forming substance precursor is 0.07 or more. 
   
     
     
         2 . The on-press development type lithographic printing plate precursor according to  claim 1 ,
 wherein a molar absorption coefficient ε at any one of the maximal absorption wavelengths in the color forming substance is 35,000 or more.   
     
     
         3 . The on-press development type lithographic printing plate precursor according to  claim 1 ,
 wherein the color forming substance precursor is a leuco colorant.   
     
     
         4 . The on-press development type lithographic printing plate precursor according to  claim 1 ,
 wherein the color forming substance precursor is an acid color forming agent.   
     
     
         5 . The on-press development type lithographic printing plate precursor according to  claim 1 ,
 wherein the color forming substance precursor includes two or more kinds of color forming substance precursors.   
     
     
         6 . The on-press development type lithographic printing plate precursor according to  claim 5 ,
 wherein the color forming substance precursor includes two kinds of color forming substance precursors.   
     
     
         7 . The on-press development type lithographic printing plate precursor according to  claim 1 ,
 wherein in the color forming substance, the maximal absorption wavelength in the wavelength range of 380 nm or more and less than 580 nm, at which the absorbance difference with respect to the color forming substance precursor is 0.1 or more is a maximal absorption wavelength in a wavelength range of 500 nm or more and less than 580 nm, at which an absorbance difference with respect to the color forming substance precursor is 0.1 or more.   
     
     
         8 . The on-press development type lithographic printing plate precursor according to  claim 1 ,
 wherein in the color forming substance, the maximal absorption wavelength in the wavelength range of 580 nm or more and 750 nm or less, at which the absorbance difference with respect to the color forming substance precursor is 0.07 or more is a maximal absorption wavelength in a wavelength range of 580 nm or more and 660 nm or less, at which an absorbance difference with respect to the color forming substance precursor is 0.07 or more.   
     
     
         9 . The on-press development type lithographic printing plate precursor according to  claim 1 ,
 wherein a ring-opening rate of the color forming substance precursor, which is determined by the following expression, is 40 mol % to 99 mol %,   the ring-opening rate=a molar absorption coefficient of the color forming substance precursor to which 1 molar equivalent of acid is added/a molar absorption coefficient ε of the color forming substance generated from the color forming substance precursor×100.   
     
     
         10 . A method of preparing a lithographic printing plate, comprising:
 exposing the on-press development type lithographic printing plate precursor according to  claim 1  in a shape of an image; and   supplying at least one selected from the group consisting of a printing ink and dampening water on a printer to remove an image-recording layer in a non-image area.   
     
     
         11 . The method of preparing a lithographic printing plate according to  claim 10 , further comprising:
 identifying the exposed lithographic printing plate precursor by a sensor.   
     
     
         12 . A lithographic printing method comprising:
 exposing the lithographic printing plate precursor according to  claim 1  in a shape of an image;   supplying at least one selected from the group consisting of a printing ink and dampening water on a printer to remove an image-recording layer in a non-image area and to prepare a lithographic printing plate; and   performing printing by using the obtained lithographic printing plate.   
     
     
         13 . The lithographic printing method according to  claim 12 , further comprising:
 identifying the exposed lithographic printing plate precursor by a sensor.